canonical way to detect platform/distribution

[Brian Reichert <reichert numachi com>]

I'm trying to design a spec file that does different things depending
on the distribution.  But, I can't see a canonical way of doing it.

My current development platform is CentOS 5.1.

On this list, and on the net, I've seen this construct

  %if 0%{?fedora} > 4 || 0%{?rhel} > 4
  # do stuff
  %endif

or this:

  %if 0%{rhel_version}%{centos_version} == 0
  # do stuff
  %endif

but none of these sorts of macros seem to be defined by the rpmbuild
universe.

'rpm --showrc' doesn't seem to provide any clues about distribution or
platform.

Any advice out there?  Pointers welcome...

-- 
Brian Reichert				<reichert numachi com>
55 Crystal Ave. #286			Daytime number: (603) 434-6842
Derry NH 03038-1725 USA			BSD admin/developer at large